I'm 100% sure it use com3 and 4, but thank's for the hint , my irq setting were wrong. (they were set in my software to irq5 and irq9 )

Also , Iâ€™ve been told it use to work only on a certain type of serial card, This card is using a 16c650 uart. From the datasheet this uart is using a 32 byte Fifo, compare to the more common 16c550 16 byte fifo , maybe this can have and impact ? Do you think your code is easily modifiable for this ? I still havenâ€™t been able to compile the hole project on my own , but if you think it feasible I'll try harder.

Ok, I need some help. I have installed your patch along with the dlls. And I am still getting an error when DOSBox tries to access the serial port. Error on the DOSBox status is "BIOS INT14: unhandled call AH=81 DX= 0"

I had it set to create a serial log file, it does it, but there is nothing listed in it.

BTW I am running Windows 2000 and I am trying to program a Kenwood radio.

As far as I know, all you need is the cable and the software. I cant find anything that mentions needing a driver. The cable is supposed to do all the conversions from and to RS232 and the TTL (5 volt) logic. So that link you sent me, how do I use those settings?

Ok great , I didn't thought the serial10.diff could be source code , sorry for my ignorance.

Do you know if version10 will eventually be incorporated into the main dosbox ?

Iâ€™m a bit concerned that I still get a bunch of error like
Serial9600: Desired serial mode not supported (5,0,0,4
Serial9600: Desired serial mode not supported (5,0,0,4
But even with those , itâ€™s working, maybe Iâ€™m to perfectionist ?